Hyperaldosteronism induces left atrial systolic and diastolic dysfunction.

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Molecular Cardiology

Background:

• Patients with hypertension and hyperaldosteronism face higher stroke risks than those with essential hypertension.
• Aldosterone's role in atrial dysfunction and thromboembolism requires further investigation.

Purpose of the Study:

• To assess the effects of aldosterone on left atrial function in a rat model.
• To explore aldosterone's potential contribution to thromboembolic events.

Main Methods:

• Rats received subcutaneous aldosterone via osmotic mini-pumps for 8 weeks.
• Evaluated left ventricular pressure-volume, atrial function, and myocyte Ca2+ handling.
• Assessed sarcoplasmic reticulum Ca2+ content, release, and phospholamban phosphorylation.

Main Results:

• Hyperaldosteronism did not cause left ventricular dysfunction or affect atrial size/filling pressures.
• Significant reductions in atrial contractility (A wave, active work index) and increased filling pressures (V waves) were observed.
• Atrial myocytes showed decreased contractility, Ca2+ transients, sarcoplasmic reticulum Ca2+ content, and reduced Ca2+ ATPase activity.

Conclusions:

• Hyperaldosteronism directly induces atrial systolic and diastolic dysfunction in rats.
• This dysfunction is linked to impaired Ca2+ handling and reduced phospholamban phosphorylation.
• The findings suggest a causal link between hyperaldosteronism and decreased atrial function, potentially increasing stroke risk.